This summer I’ve been enjoying a new receiver which has terribly cheaply (for just 16.82€, or $19.20!!!!) joined the rest of my radio material. It is an ezcap ezTV645 DVB-T USB dongle and yes, you’ve read well, it is nothing more than… an USB dongle normally used to watch DVB-T TV broadcasts (DVB-T is an European standard for digital TV) in a computer!!! This highly performing device (specially when one considers its price) is my very first SDR (Software Defined Radio) receiver and has allowed me to have my very first succesful experiences in the SDR world!

It seems that USB DVB-T dongles work according to the same principle with which specific SDR USB dongles (the FUNcube Dongle being the only example) work. They use a tuner and an A/D (analog to digital) converter, which samples the output signal of the tuner, converts it to digital and sends it to the computer via the USB port. There, in the computer, a specific software takes this signal and carries out the demodulation task.

(More on SDR will be explained in a future entry; but let me only say that the advantage of SDR equipment is precisely this: to reduce the amount of physical electronic components to a minimum expression, as most of the work is carried out through software and not through “hardware” like “normal” receivers or transceivers).

Well, so what happens is that those (and for the moment, only those) DVB-T Digital TV dongles which contain both the Realtek RTL2832U A/D chipset (which gives this practice of SDR the name of RTL-SDR) and either the Elonics E4000 or the Fitipower FC0012, FC0013 or FC2580 tuners, through the use of special drivers, can be made to work as SDR receivers so as to listen to almost any kind of radio transmission in a vast (very, very vast…) frequency range.

The tuner which provides a wider frequency coverage is the E4000, from approx. 53 MHz to 2200 MHz, with a gap between, approx., 1113 MHz and 1244 MHz. The Fitipower tuners’ range is not as large, but they have an advantage in that they can receive lower frequencies. Also, and the same way it happens with the FUNcube Dongle, an external frequency upconverter can be connected between the antenna and the dongle so that all signals in frequencies below the dongles’ coverage, in bands such as HF and lower (in fact, as low as DC! 😀 ) are brought into the range of the dongles and can be received with them! Anyway, and using an upconverter or not (and like it happens with all SDRs), all kinds of radio signals can be received: voice (SSB, DSB, AM, FM narrow and wide), CW, even digital transmissions (such as GPS, ADS-B -which is used by aircraft transponders-, POCSAG; and ham digital modes such as APRS/Packet, D-Star, PSK, RTTY…) can be decoded using the proper software. Add to this that it is possible to display, in the SDR software, an in-screen reception spectrum with a bandwidth as large as 3.2 MHz (selecting a sample rate of 3.2 MSPS -Mega Samples Per Second-) and we have an astounding device!!!

At the beginning of the SDR experiments with these devices, they were used (in Windows) with known SDR softwares such as Winrad, HDSDR, or WRplus, through an external DLL controller, named ExtIO (which can be found here: http://wiki.spench.net/wiki/ExtIO_USRP). In Linux, the GNU Radio or gqrx softwares can also be used.

Recently, a new SDR program for Windows has appeared which adds a native support for RTL2832U-based DVB-T dongles. Its name is SDR# (read SDR Sharp) and it avoids the use of the ExtIO DLL which was pretty troublesome, while offering an excellent performance, and a lot of new functions (such as the demodulation of WFM -Wideband FM; used by the common commercial broadcast stations in VHF- in stereo!!!). It is a new software which is in constant development and including new functionalities, so be sure to check regularly its website (www.sdrsharp.com) for the latest released version. A good practice is to regularly download the newest version from here: http://sdrsharp.com/downloads/sdr-nightly.zip. To carry out the installation of SDR#, and of the driver which transforms the DVB-T dongle into a SDR receiver, detailed instructions can be found here.

Well, so focusing in my experience with RTL-SDR, I’ll say that my specific unit of dongle is, as I’ve already mentioned, an ezcap ezTV645, which contains the RTL2832U chipset and the FC0013 tuner. I bought it for just 16.82€ ($19.20) at dealextreme.com (http://www.dealextreme.com/p/mini-dvb-t-digital-tv-usb-2-0-dongle-with-fm-dab-remote-controller-92096?item=1). And although a small whip antena in a small magmount is supplied with the dongle, I quickly realized that it would provide a very poor reception to me (if I could receive anything with it), so I quickly discarded it. Instead, and to be able to use this dongle with any of the antennas I also use with my IC-R5 scanner (which connect to it through standard ham radio connectors: male SMA or male PL -with a PL-SMA adapter-) I homebrewed a simple antenna connector adapter, which is nothing more than a very short pigtail of RG-58 coaxial cable, with an European TV (“Belling-Lee”, IEC 169-2, or PAL) male connector in one end, and a female PL connector (or SO-239) in the other end. Also, I needed to perform minor surgery to the innards of the dongle. It happens that ezcap ezTV dongles are not supplied with an ESD (ElectroStatic Discharge) protection diode, although its location is clearly marked near the antenna connector in the circuit board. It is just like the factory had forgotten to add those diodes to the dongles… So I had to buy a pack of 10 BAV99 diodes at a local electronics store and carefully solder one of them in its correct location. Without this diode, using an antenna placed outside, which could very possibly be charged with static electricity as a result of the friction with the wind, would have supposed a risk too high of frying the dongle. There have been people who have destroyed their unprotected dongle’s electronics by just touching the antenna connector with a finger. So this ESD protection diode is a must! Thanks to it, I’ve been able to finally stop being forced to keep the antenna inside the house when using the RTL-SDR, and improve my reception conditions with it 🙂

Some pictures follow (click on them to enlarge):

The moment of the unpackaging, right after the arrival of the package at home.

The box containing the ezcap ezTV645 and accessories, right after going out of the package.

The unboxing. Also visible is the PAL-female PL adapter pigtail.

The ezcap ezTV645 DVB-T dongle, viewed from its aft end.

Detail of the female PAL connector in the back of the dongle.

Closer detail of the female PAL connector in the back of the dongle.

The standard USB port in the front of the dongle.

The whip antenna, mag-mount, and optional sucker, supplied with the ezTV645 dongle.

The homemade connector adapter pigtail, seen from its back end.

The homemade connector adapter pigtail, seen from its front end.

Closer detail of the PAL connector in the adapter, which fits into the antenna connector in the ezTV645 dongle.

Closer detail of the SO-239 connector in the adapter, where the coax cable from the antenna connects.

The innards of the ezTV645 dongle. View of the BAV99 ESD diode, soldered in its place the best way I could do it 🙂

The innards of the ezTV645 dongle. General view of the dongle’s circuitry, with the BAV99 ESD diode installed.

The innards of the ezTV645 dongle. Detail of the back part of the circuit board, with the BAV99 ESD diode installed.

Well, so after finishing these dongle-related operations, how well does it work? Well, I can say that all the times I’ve used it it has performed flawlessly. Running the great SDR# software (which lacks an S-meter in my opinion, something that would be a great addition) in a HP Pavilion dv6-3182es laptop PC originally intended for flight simulation (CPU: Intel I7 720 @1.60GHz; RAM: 4.00GB; OS: W7 Home Premium 64-bit) it flows fantastically: as smooth as silk. As long as I don’t select a sample rate value higher than 2.048 MSPS, which provides me with a displayed spectrum almost 2 MHz wide (with a higher sample rate value the audio starts stuttering), the operation of the software is very stable, and there are no stutters, no cuts in the audio, nothing strange at all. As far as the reception is concerned (and setting the gain at its maximum position), this cheap RTL-SDR dongle has demonstrated to me to have a surprisingly good sensitivity (not like my IC-R5’s acute “ear”, but close…). Another point to highlight would be the really great stereo audio quality when listening to a common VHF broadcast station. Also, I had never had before the ability to have all the activity in the entire 2m amateur radio band in view at the same time, or to simultaneously monitor the activity in all the LEBL (Barcelona-El Prat airport) approach (or ground, or radar…) frequencies in the air band. I also had never had before a receiver which by default came with the capacity to demodulate SSB signals, and this is very important to me, as it means that I’m able to, for the first time, listen to SSB satellites. I’m not restricted anymore to only picking the AO-27 and SO-50 LEO FM satellites, as well as the ISS; now I can also listen to the downlink of VO-52 at 145.900 USB!!! It is awesome to think of all the things that can be made with such a small (and cheap!) device…

Listening to the local VHF broadcast station RAC105. The traces of adjacent stations can be seen, as well as the huge bandwidth these stereo signals have. It is also possible to observe how the software is trying to decode the RDS information contained in the transmission. The discontinuity in the waterfall (where, in the moments of silence, the unmodulated stereo carriers can be seen) corresponds to the typical time signals (“beeps”) most stations use. (Click on the image to enlarge).

Monitoring the LEBL (Barcelona-El Prat airport) Approach and TWR (Tower) sector communications in the air band. 118.100 is TWR for landings; 118.325 is TWR for takeoffs; 118.650 is the ATIS (Automatic Terminal Information System) for landings; and 119.100 is the Approach frequency. (Click on the image to enlarge).

Listening to a local QSO in the 2m ham/amateur radio band. (Click on the image to enlarge).

Decoding the ISS Packet/APRS stream on 145.825!!! (+/- the frequency shift due to the Doppler effect) The Packet decoder software used is the UZ7HO Soundmodem available here. (Click on the image to enlarge).

Decoding the local terrestrial Packet/APRS signals, also with the UZ7HO Soundmodem software available here. (Click on the image to enlarge).

Listening to the downlink of the ham/amateur radio satellite VO-52 as it makes its pass!!! (Click on the image to enlarge).

The SDR nature of this receiver makes me able to see things I had never been able to see before!!! In this case I can actually take a look at the shape of a local and unidentified interference which appears in the afternoons. How cool is this. (Click on the image to enlarge).

There are some minor drawbacks, though: in a first place, a small impedance mismatch at the antenna connector of the dongle (which has the standard impedance for all commercial radio and TV equipment of 75 ohm, vs the 50 ohm impedance used in all ham radio equipment), which in theory causes a signal loss (however, this loss is very small, so it is not a big issue; and if necessary, I could solve it through the use of an 1:1.5 unun). Secondly, there’s a small delay in the sound, about half a second or so, in comparison to a conventional receiver such as my IC-R5 (which is the time taken in the process of converting the signal to a digital format, and transferring it to the computer via the USB port; it is not a big problem if I don’t listen to the IC-R5 and the RTL-SDR at the same time on the same frequency!). And in third place, it happens that a very strong signal in one frequency easily inhibits the reception in the rest of the displayed spectrum, this is, this receiver becomes easily saturated (even if the gain is at the minimums); again not a big problem, as strong signals, at my location, appear only sometimes; and it its something I can live with.

So what’s the conclusion? Considering its high performance, its wide frequency coverage, its reduced price and the new reception capabilities this brand new SDR receiving rig has personally provided to me, and also given the small relevance, in my personal case, of the drawbacks it presents, I’ll say that it is an outstanding device, very versatile and with a lot to explore. I extremely recommend it. Get an RTL-SDR dongle. It’s an awesome receiver!!! 🙂

Thanks! As a student, these days I’m a bit busy so I can not update the blog as frequently as I would like, but I’ll say that these Christmas holidays I’ve received a brand new HF upconverter from CT1FFU… This and a homemade wire dipole will be the source for a lot of fun in the upcoming days!!! I’ll try to write an “RTL-SDR update entry” as soon as I can 😉

(I also have to write some kind of a review for the Tecsun PL-600 receiver that has come these holidays too!!! 🙂 )

Hello David,
its a beatiful article. Can I use some comments and Pics for an article tha write for my Ham Magazine 5-9 Report ?? ( http://www.5-9report.gr )
I will put you on the sources.
73s de SV5BYR

David,
Thanks for the great site. I have (I think ) downloaded all the necessary stuff to make the dongle run. However, I still am unable to make the software work. When I click on the ExtIO button on the tuning display, it says it can’t find the dll file. I hav downloaded everything I ccan find and have put the dll file into the SDR install file. Can you point me to the resources on the web that are the most straighforward? Any help is appreciated, as I would really like to get this working. I’ve downloaded everything once – it wouldn’t work. Then I uninstalled everything and re-installed it.

Also, the waterfall display is picking up ambient noise from the room, so the sound card isn’t configuring, either.

Perhaps you are trying to run the dongle with the ExtIO dll using HDSDR or some similar software… I’ve got absolutely no experience with this combination, but what I can say is that as far as I know this is an older setup or a solution of compromise that was used before other software offered native support for RTL-SDR.
If you install SDR# or SDR Console (or both 🙂 ) you should be able to get the dongle running soon and with a better performance than when using the HDSDR-ExtIO.dll combination.

HI,
Thanks for the reply regarding the downloads. I re-downloaded SDR# and it all sprang to life! What a neat piece of technology! A lot of bang for the buck to boot!
After having familiarized myself with amateur radio astronomy some years ago, I can see a definite application here – it easily covers the prime listening spot called “the watering hole” at about 1.42 ghz.
Has anyone seen much traffic on blog posts or user groups on the use of the dongle for amateur RA?
Thanks again.
Ken

Hi, for the moment I’ve been trying the Digital Master software in the Ham Radio Deluxe set of applications. A couple days ago, I tried to decode some PSK-31 transmissions in the 20 meter band from a WebSDR receiver located in Andorra and I succeeded. Then, I connected the headphones output of my Tecsun PL-600 receiver to the microphone input in my laptop computer and, despite the noise that the laptop put on the receiver, the software did a nice job on decoding quite well the same signals. So a nice piece of software that, as far as I’ve been able to appreciate, works well.

Also, there’s a whole lot of other software for decoding digital modes. One good page I came across about it is this: http://www.qsl.net/rv3apm/ . Check it out! One of these days I’ll have a try on some other software from this page to see how it works too.

I’ve still not tried to decode from my RTL-SDR but I suppose that if it worked with the WebSDR it should work well too with the RTL.

WOW! You know, if you sold pigtails like that, it may just be a lucrative little business. I haven’t been able to find one on the internet yet. Seems easily done, but TIME consuming. Lets put it plainly…I’d buy a couple from ya! Great article/post. Keep it up. Thanks

Hi, sorry for the late reply and the general lack of blog activity, I’m a busy student and I still don’t have holidays… 🙂

If you have installed the Zadig drivers now all what you need to do is to go to the “downloads” section in the SDR# website and download the “SDR# RTLSDR Plugin”. Overwrite the files in the folder where you’ve placed your SDR# with the ones in the zip file you’ve just downloaded (do not copy the “config” subfolder you will also find in the zip). Use the Notepad to open the “SDRSharp.exe.config” file located in your SDR# installation folder and do the following:

In the “frontendPlugins” section, remove the marks that are disabling the line where the following text is present:

Hi all, and very good article David!
In hope to help some newcomer who would like to give it a try, here is some more useful info:

– The best software to use IMHO is SDRSHARP, (http://sdrsharp.com/) . Here is a “magic” script from their website which will auto-download it and do the most part of setup for you:http://sdrsharp.com/downloads/sdr-install.zip .
Unzip it in a folder then launch “Install.bat”. After that, don’t forget to run the “Zadig” utility to install the USB driver to complete your setup, or it will never work. You will find zadig.exe in “sdrsharp” folder after the script have finished setup, but FIRST read the easy explanation that you will find here:http://rtlsdr.org/softwarewindows

– There are many RTL2832U’s based dongles, carrying several kind of tuners. The most famous combination is the RTL2832U + E4000 tuner, which seems to be able to tune the largest band (with a gap, as David already told). They are harder to find because the E4000 tuner is no more in production. BUT… I’ve tried many other tuners/USB dongles and I’ve found that the RTL2832U + R820T based dongles are far better than the E4000 based dongles. They are MORE sensibles vs faint signals, really. The reverse side is that they don’t cover frequencies over 1600 Mhz (but they starts around 22 Mhz, even if at that frequency there are many “dirty” signals coming -perhaps- from the pc. Need some filtering…).
You can find many **cheaps** RTL2832U + R820T based dongles on ebay, coming mostly from China. They all works well, the only disadvantage is that they carry an MCX connector and so you will need some kind of adapter to connect it to an external antenna. Lately some seller will use to add some adapter to the bid, take a look for it. Or you can try cutting in the middle the cable of the mini antenna sold with the USB stick, and solder a BNC or a common TV or some other kind of connector to the other side of the cable connected to the MCX plug. Keep in mind that this will be a good solution for testing, but this cable doesn’t seems to be shielded so it will easily pick up some interference.

– To decode digital modes, NOAA satellites and so on you must use appropriate softwares (some of them are free), and another one which is called VAC (virtual audio cables) (not free). The latter one is necessary to create an internal virtual connection from the audio output of Sdrsharp to the input of the decoding software.

I am interest to wonder if can use these SDR to make fish radar. Does anyone know of project that does fish radar. I prefer not make my own and get already made one but can make it if I have the plans.

Hi. Thank you so much for this really clear and useful article! I’m just starting with SDR and this has been for me, by far, the most clear and useful help that I’ve found.
I already ordered my USB dongle but, meanwhile, I’ve heard and read a lot about that the antenna that comes with the USB is not good at all. Have you worked on that? Do you have any advice about a good DIY antenna option for my new RTL DSR dongle? Thanks in advance for your help with this matter! Regards.

Firstly, I need to apologize for not having been able to update the blog in a lot of time. I’ve not had a lot of free time during the past months and this prevented me from maintaining it.

Secondly… Yes, you are right, the stock antenna that can be found with the dongle is very poor at receiving signals. Even at TV frequencies, for which the antenna is designed. I have to say that almost immediately after taking one of those whips out of the box I left it aside, but one day I decided to test it with my digital terrestrial DVB-T decoder and got no signals. I’ve not used any of them anymore… My advise would be the usage of any standard antenna that was cut for the center frequency of the band you want to cover. For example, in my case, I am currently using a Diamond SG7900 ham radio mobile antenna that is a dual bander designed to cover the amateur 2m (144 MHz – 146 MHz) and 70cm (430 MHz – 440 MHz) bands. I use it for listening to other VHF and UHF frequencies as well, because at the present moment I’ve not been able to install more antennas in my main QTH at Barcelona. For listening in the HF bands, I use an easy DIY antenna (not a great performer but like the ham radio saying, any antenna is better than no antenna at all): 12.6m of standard electrical copper wire, and a 9:1 unun. The unun lowers the high impedance the wire presents at some frequencies, to the 50 ohm impedance of the coax cable. The signals arrive then at an upconverter before being fed into my RTL dongle (the complete HF segment falls out of the coverage of those dongles and so the usage of a frequency upconverter is normally necessary). If for starting you would like to DIY something that is extremely easy and simple, and cheap to do, for bands from VHF onwards, I can recommend the “MSI” GP type antenna. You can find more about it here: http://www.pedrolo.com/index.php/antenas/proyectos-sencillos-de-antenas-caseras/49-antena-msi-mas-simple-imposible . The only materials required are: a SO-239 type connector, conductive copper or aluminum rod, power clamps, an a screwdriver. This is the antenna I made for covering the airband although I’ve not been able to install it yet! I had made it before for the ham radio 2m/70cm bands and it performed amazingly. I could even receive readable signals from ham radio satellites on low elevation passes. Try it!

You’re so cool! I do not suppose I’ve read through a single thing like this before.

So good to discover someone with a few genuine thoughts on this issue.
Really.. thank you for starting this up. This web site is one
thing that is needed on the internet, someone with a little originality!

Hi there, great information! So thanks!
Should be possible to swap the 50ohm connector of that dongle, with a 75ohm connector. I know 75ohm connectors are bigger, but they should have to fit if the plastic case of dongle is modded…
what do you think about it? worth it?

An intriguing discussion is definitely worth comment.
I do believe that you should write more on this subject
matter, it might not be a taboo matter but usually people do not
discuss these subjects. To the next! Kind regards!!